Microstrip phase shifter having phase shift filter device

Abstract

A broad band phase shifter of the present invention can be used in a microstrip conductor and includes a power divider disposed along a microstrip conductor. The power divider has first and second outputs. A reference transmission line is disposed on the microstrip conductor and connected to the first output of the power divider. A phase shift filter device is disposed on the microstrip conductor and connected to the second output of the power divider. The phase shift filter device comprises a 180 degree phase shift coupled line structure formed of a first substantially linear 90 degree phase shift parallel line section, and a second substantially linear 90 degree phase shift parallel line section coupled to the first parallel. line section. The first and second 90 degree phase shift parallel line sections have parallel lines that are spaced about five mils apart. The first and second 90 degree phase shift parallel line sections also have parallel lines that are offset to each other.

That which is claimed is:  
     
       1. A three bit phase shifter comprising: 
       a 45 degree phase shift filter device disposed as a first microstrip structure, said 45 degree phase shift filter device comprising a 90 degree phase shift filter device having a substantially “U” shaped first reference transmission line and a substantially “U” shaped first phased transmission line having a radial stub for subtracting 45 degrees, wherein said “U” shaped phased transmission line has a width less than the width of said first reference transmission line;  
       a 90 degree phase shift filter device disposed as a second microstrip structure and operatively connected to said 45 decree phase shift filter device, wherein said 90 degree phase shift filter device comprises a substantially “U” shaped second reference transmission line and a substantially “U” shaped second phased transmission line, wherein said “U” shaped phased transmission line has a width less than the width of said second reference transmission line;  
       a 180 degree phase shift filter device disposed as a third microstrip structure and operatively connected to said 90 degree phase shift filter device, wherein said 180 degree phase shift filter device comprises a substantially “U” shaped third reference transmission line and two substantially “U” shaped third phased transmission lines, wherein said “U” shaped phased transmission lines have a width less than said width of said third reference transmission line; and  
       means for selecting said 45 degree, 90 degree and 180 degree phase shift filter devices to provide a beam in a desired direction.  
     
     
       2. A three-bit phase shifter according to claim  1 , wherein said means for selecting said 45°, 90° and 180° phase shift filter devices to provide a beam in the desired direction comprises a control selector using three-bit inputs to obtain a desired angle. 
     
     
       3. A three-bit phase shifter according to claim  2 , wherein said control selector can select angles based on 45 degree increments.